[Rdo-list] Outbound packet traffic with nova-network

Michael Solberg msolberg at redhat.com
Thu Jun 27 03:58:27 UTC 2013

Hi list.

I'm having some trouble with my network setup and I thought maybe the 
group could help.  I have three compute nodes with two network 
interfaces.  There's a private network (fixed range) on 
eth1 and a network (floating range) on eth0 on these nodes.

Networking works as expected.  Connectivity is good on the 192 network 
and traffic is forwarded from the floating range inbound to the fixed 
range correctly.  That is, I can ssh into an instance from the outside 
world using the floating address.  However, when traffic is leaving the 
instance, it doesn't seem to get translated.  Here's a concrete example:

Instance has a fixed address of
Instance is assigned a floating address of
Instance is running on a hypervisor with the address

Pings from the instance to return fine, but pings from the 
instance out to the internet don't work.  When I run a tcpdump, I see 
that the pings reach the destination with the source address set to

[root at ~]# tcpdump -n -i eth0 icmp
tcpdump: WARNING: eth0: no IPv4 address assigned
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes
23:55:38.238739 IP > ICMP echo request, id 
45321, seq 1, length 64
23:55:38.238774 IP > ICMP echo reply, id 
45321, seq 1, length 64

Is this expected?  If so, is there any way to get nova-network to 
translate the outbound traffic so that it looks like it's coming from instead of


Michael Solberg
Principal Architect, Red Hat, Inc.

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